In recent years, in various devices such as a semiconductor device and a display device, in order to realize an improvement in function, their structures have become smaller and complicated. Especially, an element or wiring forming each device becomes a laminated structure in which thin films of several-atom levels have been overlapped, and a demand for observing that structure is high. For this reason, one general technique is that the lamina is taken out by forming it by using a focused ion beam in a sample surface predetermined place, and it is observed by a high resolving power microscope such as transmission electron microscope.
Hitherto, there is known a method in which, by using a composite apparatus comprising a focused ion beam irradiation system and an electron beam irradiation system, the lamina sample is made by sputtering-etching-working a desired place of the sample surface by the focused ion beam, the lamina having been made is taken out, and the lamina sample having been taken out is observed by the transmission electron microscope (for example, refer to Patent Document 1).
[Patent Document 1] JP-A-4-76437 Gazette (2nd page)
[Patent Document 2] JP-A-4-62748 Gazette (2nd page)
With a development of a device manufacturing technique, the structure of an object to be observed becomes fine. In order to observe this fine structure, although the transmission electron microscope is utilized, in order to observe the fine structure by the high resolving power microscope, there is shown the fact that, when performing a lamina sample making for the observation, damage to the lamina sample when the sputtering etching working by the focused ion beam (FIB) has been performed is made minimum and, at the same time, a shape confirmation of the lamina sample is performed in a scanning electron microscope (SEM) observation by an electron beam irradiation scan.
As shown in the Patent Document 2, in order to uniformize a thickness of the lamina sample, it is known to work the sample while being slanted. However, in such a working method, a method of controlling the thickness of the lamina is not known.
The present invention solves the above issue, and its object is to make it possible to accurately control the thickness of the lamina and, at the same time, make the lamina sample in a short time.